Wire and plastic conveyor belt systems are widely used in a great variety of industrial fields. A wire mesh or plastic overlay can be used with the rods to provide a support surface of a conveyor belt. The wire or plastic components of the overlay are intermeshed together by connecting rods which extend transversely across the width of the belt. Typically the intermeshed overlay components are connected to one another by the connecting rods. Alternatively, the support surface provided by the rods can be used without an overlay. The ends of the rods are inserted into connective links and the rods and links are welded together. The connective links may serve as tractive links around a sprocket wheel.
In conventional conveyor belts, a weld is typically placed at the exterior sides of the link legs to attach the link to the rod. This weld serves two purposes. Firstly, it achieves positive fixation of the link to the outermost portion of the rod. This is important because the connective links at the outer edges of a belt are used for driving interface with the drive sprockets so that any transverse or lateral movement of the connective link along the rod will result in misalignment with the sprockets. This will lead to damage to the sprockets, belt and the system. Secondly, the weld prohibits the connective links from rotational movement that leads to "tenting" of the link on the rod. Tenting refers to the rotational movement of the link relative to the rod when the rods move together causing a link to tilt upward about its rod apertures, and is illustrated schematically in FIG. 16. This movement normally occurs on the inside edge of the belt during its collapsed state of operation in a spiral system, and causes the belt to jam during operation resulting in belt and system damage, as well as downtime.
The weld holding the link to the rod is a main area of perceived failure and real failure for conveyor belts since the weld is subjected to numerous stresses during operation. The biggest contributors to weld failures include normal fatigue caused by belt tensions above the allowable limit including lateral deflection of the legs of the connective links and rod buckling. These stresses on the links cause cracks to form in the welds. Even after a weld fails, however, it continues to function to hold the connective links in a fixed position which allows the belt to operate. It has been observed that the weld deposits on the rod act as barriers that trap the connective link in place allowing for proper sprocket and drive engagement. In addition, while tenting has been observed where welds have failed, in general the ragged edges of the fractured welds continue to prevent rotational movement of the connective link.
A conveyor belt with fractured welds is acceptable and operational as long as the system is running under allowable tension limits, however, the problem of perceived failure of the belt arises whenever some of the welds are cracked. Even though a belt with cracked welds is still able to function effectively under normal operating conditions, users who have been repeatedly warned by belt manufacturers that broken welds are precursors to real failure have perceived the broken welds as a failure in and of themselves. There has been a need to structurally affix the links on the rods to prevent their rotation about the rods. This engagement would eliminate this perceived problem with conventional belts that raises user complaints and warranty issues.
Besides showing the first signs of fatigue stress, the conventional welds between the links and rods also require a time-consuming manual welding step during manufacture. As can be seen from FIGS. 12-14, the conventional methods require that the connective links be individually welded to the rods. This step is inefficient and expensive.
In conveyor belts used to move consumable material through processing machinery, such as coating, freezing, cooking, etc., sanitation is a concern particularly in conveyor systems which present a variety of crevices into which the material can be deposited and spoil. In conventional conveyor systems, the belts must be cleaned periodically, particularly in the welded area.
Therefore, there exists a need for a conveyor belt with structural features that will eliminate the time consuming welding step and thereby eliminate perceived and real weld failure, decrease the chances of tenting of the links, and presents a conveying surface with less crevices for sanitary operating conditions. There also exists a need for streamlining the manufacture of conveyor belts by eliminating the current methods of attaching the connective links to the rods.